Reduction of oxidative cell damage by an anthocyanin/polyphenolic rich fruit juice in an intervention study with patients on hemodialysis.

B12

Patients with chronic renal failure undergoing hemodialysis (HD) are considered to face an elevated risk for cancer, artheriosclerosis and other diseases. This has been attributed in part to increased oxidative stress, resulting from bioincompatibility of the extracorporal blood circuit, malnutrition and other factors. Uptake of fruit juice with especially high flavonoid/polyphenol content has been shown to reduce oxidative cell damage in healthy probands (Weisel et al. Biotechnol. J., 1, 388, 2006) and might also be utilized as preventive measure in HD-patients. An intervention study is performed with mixed fruit juice (total phenols: 3478 mg/L). After a three week run-in phase (R), 20 HD-patients (non-smokers, stable HD) consume for 4 weeks 200ml/d of the juice (juice uptake phase: J), followed by a three week wash-out phase (W). Blood sampling is performed weekly. DNA damage (COMET assay with/without formamidopyrimidine-DNA-glycosylase) and glutathione (kinetic photometric assay) in whole blood are monitored. Additionally, lipid peroxidation (HPLC/fluorescence of malondialdehyde), protein oxidation (carbonyls, photometrically) and the trolox equivalent antioxidant capacity (TEAC) are determined in plasma. Transcription of catalytic and modulatory subunits of γ-glutamate-cysteine ligase (γ-GCl), catalyzing the rate-limiting step of glutathione synthesis is analyzed by quantitative TaqMan PCR. DNA binding capacity of the transcription factor NfκB (ELISA) is monitored in primary blood mononuclear cells. First results (obtained from 13 patients) show a strong decrease of total DNA damage (with FPG) during juice uptake (mean TI%: R: 5.3/J: 3, p<0.0005; J: 3/W: 3,9, p<0.0005), basic DNA damage (without FPG) was also reduced (mean TI%: R: 0.61/J:0.51, p<0.05; J: 0.51/W: 0.44, p=0.054). Correspondingly, an distinct increase of total glutathione (R/J and J/W, both p<0,0005), glutathione status (R/J and J/W, both p<0.0005), and of γ-GCl expression (especially of the catalytic subunit) occurred during the intervention. Lipid peroxidation, protein oxidation and NFkB-DNA binding activity were slightly reduced during juice uptake (malondialdehyde: R/J, p<0,01; protein carbonyls: R/J, p<0,05; NfκB: R/J, p<0,005); an increase of antioxidant capacity (TEAC), however, was not observed (R/J, p>0,05). In conclusion, the red fruit juice clearly shows a marked potential to reduce (oxidative) cell damage and elevates glutathione synthesis in HD-patients. These effects can be attributed to its high content of flavonoids/polyphenols. (Supported by Karin Nolte Foundation)